The present invention relates to a back-up shear plate or shim plate for metal frame windows.
Metal frame windows usually include vertically and horizontally oriented elongated hollow bodies with inwardly disposed wall elements (in a direction towards the glass window pane), front and rear wall elements (which may be exterior and interior faces, respectively) and outer wall elements. The outer wall elements are opposite the inwardly disposed wall elements. The inwardly disposed wall elements form an inwardly facing U-shaped or C-shaped channel adapted to retain a window pane therein. The window pane is placed in the U-shaped or C-shaped channel with a gasket, caulk or other type of sealant placed along the front and rear intersecting joints between the U-shaped channel of the metal window frame and the glass pane.
The metal window frame elements, which are the aforementioned elongated hollow bodies, surround the periphery of the window pane. Although reference herein is made to a singular window frame elongated hollow body, the back-up shear plate described herein is used at predetermined locations on each of the horizontal window frame members and vertical window frame members. Typically, back-up shear plates are placed four inches from each corner of the metal window frame and nine inches from the mid-point of each window frame run, that is, nine inches on either side of the center point of the upper and lower horizontal window frame elements and the left and right vertical window frame elements.
Back-up shear plates are customarily made of aluminum. The aluminum shear plate is extruded to form a base plate having laterally disposed interlockable members (generally female edge members) which interact with the opposing lateral wall elements forming the outwardly facing mouth of the elongated window frame hollow body. The prior art aluminum shear plates are cut in approximately four inch lengths (the longitudinal aspect of the plate) and then placed on a window frame element to cover select portions of the outwardly facing mouth of the metal window frame elongated hollow body member. Prior art aluminum back-up shear plates have a tendency to slide in the mouth of the hollow body frame. Accordingly, installers of windows were required to manually crimp at least two and typically four comers of the aluminum back-up shear plate. Further, prior art aluminum shear plates require two sets of drill bits. The first drill bit is used to drill through the aluminum back-up plate and the second drill bit is used to create a hole for the masonry screw which mounts the metal frame to a concrete column.
Also, prior art aluminum back-up shear plates do not include any self shimming elements. As known in the window installation business, after the rough opening of the window is measured, the metal window frame is constructed from extruded aluminum frame elements and then is installed in the rough opening using back-up shear plates and a plurality of shims. The shims may be wood or other types of readily available construction material. The shims are utilized to level and plum the window in the rough opening and to secure the window in the frame from shear forces. The back-up shear plates are mounted with masonry screws extending through the metal window frames, the back-up shear plates and into the vertical columns and horizontal header and footer to prevent the metal window frame from moving in the rough opening. Shear is an action or stress resulting from applied forces that cause or tend to cause two contiguous parts to slide relative to each other in a direction parallel to their plane of contact.
The present invention solves the problem of utilizing two drill bits, crimping the aluminum back-up shear plate, and, in some instances, provides self shimming structures for the window frame.
It is an object of the present invention to provide a plastic back-up shear plate for metal window frames.
It is an additional object of the present invention to provide an intermediate locking lip inboard of a break-away edge portion to permit conversion of the shear plate from a larger window frame mouth to a smaller window frame mouth.
It is another object of the present invention to provide a back-up shear plate which includes self shimming elements.
It is a further object of the present invention to provide a plastic back-up shear plate which includes support ribs for the window pane channel.
It is a further object of the present invention to provide a back-up shear plate which is spring fit into the outwardly facing mouth of the metal window frame in order to avoid further manipulation (crimping) of the shear plate in the metal window frame.
It is a further object of the present invention to provide a unique shear plate design to enable use with metal window frames, manufactured by two different manufactures, having different critical dimensions.
It is an another object of the present invention to provide a back-up shear plate which is adapted to fit on a plurality of metal window frames having different sized frame mouth openings.
It is a further object of the present invention to provide a back-up shear plate for multiple sized frame mouth openings wherein the base plate, comprising the shear plate, includes a plurality of sides equivalent to twice the plurality of different window frames.
It is another object of the present invention to provide a shim plate for a metal window frame.
It is a further object of the present invention to provide a shim plate utilizing a base plate and a buckling ribbon laterally spanning a central cutout in the shim plate.
It is a further object of the present invention to provide a shim plate which is operable for two different sized metal window frames wherein each window frame has a different sized frame mouth opening and wherein the first and second ribbons span first and second lateral spans of the shim plate.
The plastic back-up shear plate is laterally disposed with generally a spring fit into the outwardly facing mouth of a metal window frame. The outwardly facing frame mouth is formed and defined by the window frame elongated hollow body and particularly by outer wall elements which face each other in an opposing manner. The plastic back-up shear plate has laterally disposed opposite outer edge portions which are interlockable on corresponding outer wall elements of hollow body metal window frame which wall elements define the mouth of the window frame. In a perpendicular direction, the back-up shear plate has a opposing edge portions with interlock on window frame mouths having a slightly different dimension. The plastic back-up shear plate lateral lips to lock onto lateral frame mouths having different dimensions for different sized frames. The shear plate is constructed and arranged to fit, with appropriate change in orientation, window frames of two different mouth openings. Multiple window frame mouths, on different window frames, are accommodated by a multi-sided back-up shear plate.
The back-up plate may also be constructed as a shim with a buckling ribbon extending over a central cut-out on the base plate.